Fugitive US intelligence contractor Edward Snowden has opened an account on the social network website Twitter. His opening tweet was: "Can you hear me now?" In his profile, Mr Snowden says he "used to work for the government. Now I work for the public". He quickly gathered thousands of followers.

This is where I would say I'm going to put all seven of his tweets. But really I want to sound more intelligent.

.@neiltyson Thanks for the welcome. And now we've got water on Mars! Do you think they check passports at the border? Asking for a friend.